The present invention relates to a chair, more particularly to a chair with an extendible footrest.
The object of this invention is to provide a chair having a crank mechanism for moving a footrest between extended and retracted positions relative to a seat.
Accordingly, a chair of the present invention includes: a seat base; a seat mounted on the seat base, extending in a longitudinal direction, and having left and right sides, front and rear ends, and a bottom; a backrest disposed rearwardly of and connected to the seat; a footrest disposed frontwardly of the seat; a linkage mounting unit including left and right brackets fixed to the bottom of the seat and extending in the longitudinal direction, each of the left and right brackets having opposite front and rear ends; a shaft mounted rotatably on the rear ends of the left and right brackets and extending in a transverse direction relative to the longitudinal direction; an operating lever secured to the shaft for turning the same; a support unit disposed below and for supporting the footrest thereon; and a linkage unit interconnecting the seat and the support unit, and including a pair of crank mechanisms disposed at the left and right sides of the seat 11, respectively. Each of the crank mechanisms includes a first crank arm, a second crank arm, a third crank arm, and a fourth crank arm. The first crank arm is secured to the shaft for synchronous rotation therewith, extends transversely from the shaft, and has a pivot end distal from the shaft. The second crank arm is disposed frontwardly of the first crank arm, and has a front end and a rear end pivoted to the pivot end of the first crank arm. The third crank arm is of generally triangular shape, is disposed frontwardly of the second crank arm, and has a first corner pivoted to the respective one of the left and right brackets, a second corner pivoted to the front end of the second crank arm and disposed above the first corner, and a third corner disposed above the first corner. The fourth crank arm is disposed frontwardly of the third crank arm, and has a front end pivoted to the support unit, and a rear end pivoted to the third corner of the third crank arm such that rotation of the shaft and the first crank arm via actuation of the operating lever in a first direction results in turning of the third crank arm relative to the respective one of the left and right brackets in the first direction via said second crank arm, which, in turn, results in turning of the footrest relative to the left and right brackets in a second direction opposite to the first direction via the fourth crank arm, thereby stretching out the footrest to an extended position relative to the left and right brackets, and that rotation of the shaft and said first crank arm via actuation of the operating lever in the second direction results in turning of the third crank arm relative to the respective one of the left and right brackets in the second direction via the second crank arm, which, in turn, results in turning of the footrest relative to the left and right brackets in the first direction via the fourth crank arm, thereby folding the footrest to a retracted position relative to the left and right brackets.